Electric furnace and method of operating the same



Jan. 13. 1.925.

ELECTRIC FURNACE AND METHOD OF OPERATING THE SAME Filed Feb. 16, 1922 2 Sheets-sheet l 'mi u? troxuni Jan, 13'. 1925.

1,522,665 P. WRIGHT l ELECTRIC FURNACE AND METHOD OF OPERATING THE SAME Filed Feb. 16, 1922 2 Sheets-Sheet 2 Patented dan, ld, w25,

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s arent ,nnncrnrc nnnrracn ann rianne-n or ornnn'rnre Application nieu February le, i922. Serial No. 536,995.

Yand Methods of @perating the Same; and

ll doV hereby declare the following to be a full, clear, and exact 'description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to electric furnaces and has for its object to provide an apparatus for melting or smelting ores and other materials, which will be comparatively inexpensive to construct and more ethcient in action than those heretofore proposed.

With these and other objects in view, the invention consists in the novel details of construction and combination of parts more fully hereinafter disclosed and particularly pointed out in the claims.

Referring to the accompanying drawings forming a part of this specification, in which like numerals designate like parts in all the views: 1 y

Figure l is a lvertical sectional view of one form of furnace made in accor with this invention;

Figure 2 is a sectional view of a some what modified form of furnace;

Figure 8 is a diagrammatic cross sectional view of a furnace similar to 'those show'v in Figures l and 2 and illustrating stack, feed chute and a slag spout;

Figure t is a sectional view of a sti urtner modified form of the invention essen cially adapted for a three-phase current;

Figure 5 is a detail view illustrating a modified form of heating elements; and

Figure 6 is a diagrammatic view illustrata still further modied arrangement the heating'elements.

i ln order that the invention may be better understood it is said: This furnac is especially adapted for melting and smelts ing pocket ores that are found in Galifornia, Uregon, and the Pacific coast generally.. ln the regions where these ores are found, sources, of electric current are available but such sources may sometimes be single phase,

, two phase, or three phase, and therefore,

it is very desirable to adopt such a furnace as will lend itself readily to curn rents .of one or more say, as is well known, in changing from a current of one phase to a current of two or more phases, it is often necessary to change the number of electrodes, and in many cases .it is desirable to change the winding of the transformers and certain of the electrical connections. But these changes i can be readily accomplished by the skilled workmen and when furnaces of the character of those herein illustrated are adopted these said changes are readily carried out.,

Referring to the drawings, l indicates any suitable furnace walls preferably of brick work which are surrounded by the metallic casing 2 to hold the parts together, should they crack or otherwise deteriorate. 3 indicates a stack for carrying away the noxious gases, l indicates a hearth for holding the molten. material, 5 a `spout or passage to draw od the molten metal or other material, and 6 a slag spout for drawing olf the slag.

ln the form of furnace illustrated in ligures l and 2, the electrodes l0 may be readily joined in a single phase circuit indicated at il, while in the form. shown in Figure 1l, the electrodes 7 may be joined in the primary circuit 8 and 9, of the three phase system. carried by the circuit connections 8 and 9 and the induction coils 14e and l5 are located in inductive relation tol said coils l2 and 13 to feed the circuits connected therewith, That is to say, the coil lt feeds current to an electrode 16, see Figure ll, which may be one of a pair of electrodes, and the coil l5 4feeds current to the resistor heaters i8, i9

and 20, as shown1 all the forms of the furnace, the electrodes are or may be adjustable up and down by a suitable and well means not shown, and the ore or other to be melted or smelted is conveniently fed into the stack 3 by meansof the chute 2l through the opening 22 normally closed by the door 23. The furnace bodies are cut away as illustrated to form arched over roofs while in Figure i the said body cut away to form the annular space 25 as shown, The roof of the furnace bodies is provided with openings as illustrated, which openings are closed by one or more cover plates 26, provided with holes 27 through which the .electrodes are passed. The ane nular space 25 illustrated in Figure l widens out somewhat below the top of the furnace rlhe induction coils l2 and 13 are 'lll and terminates in the crucible or hearth space at the bottomfof the furnace.

The charge material, on the other hand,

Y descends through the central space 29, which extends substantially down to the :normaly level ofthe molten material and thus is prevented from striking the electrodes and me- 20. The somewhat poor contact thus provided between the element 19 and the elements 18 and 20 causes the element 19 to be readily heated up to a high temperature. This action is enhanced by so regulating the size and dimension of the element 19 as to facilitate its being raised to a high temperature, and in addition to this, in many cases the element 19 will be made of carbon, while the .elements 18 and 20 will be made of a good conducting material such as metal copper matte or magnetic iron oxide FeO. In all cases, the heatwill be concentrated in the element 19 and conducted from said element 19 to the charrue.

In order to still further facilitate t e heating of the charge, I provide at each end of the element 19 a mass of finely di- Ivided carbonaceous or other semi-conducting material 30, as shown, so that current will readily pass from the elements 18 and 20 through said material 30 and from said material 30 through the char e, as it becomes more and more heated. 2etween the carbonaceous or other masses 30 I further provide the somewhat insulating material 311 which may be conveniently made of c ay.

This entire heating element 19 is in a secondary circuit as shown, with the secondary voltage regulated to suit the conditions of the furnace. Accordingly, it results that when the current is first turned on', before the ore is heated to a high temperature a large percentage of the current passes through the carbon resister 19, heating it and the entire lower body of the furnace. As the ore gradually heats up art of the secondary current leaves the car on resister 19 and flows through the carbonaceous or chromite materials 30 and through the ore, thus increasing the heating of the latter, so that the primary electrodes 7 will begin to pass current throu h the entire charge of ore be rapidly melted.

It will be observed from Figure 2 that the elements 2O are two in number and of course it will be readily understood that the elements 18 may likewise be two in number in order to carry a greater voltune the ore, and thus will of current and to keep down the temperature in the elements 18 and 20. It will also be observed that there is a considerable space reserved in the brickwork 1 to accommodate the elements 18, 19 and 20, and that, as shown in Figure 2, this space is partially filled with a refractory material 32 which may be of clay or other well known refractory substance, so that the heating elements do not come in contact with the furnace walls. f

In addition to this refractory material 32, there is an air space 33 surrounding the carbon element 19, and thus is the said element still further. insulated from the heating walls. The refractory material 32, however, serves to effectually seal the carbon-element 19 from the outer air, and thus is the combustion of said element 19 prevented. When it is desired to renew the elements l18, 19, or 20, or any one of the same, it is only necessary to remove a few brick near the sides of the furnace to remove theelements 18, 19, and 20, and to slip in a new assemblage of elements 18, 19, and 20, which have been prepared on the outside of the furnace, whereupon the space may be readil bricked up at each side of the furnace andY the new carbon element 19 sealed in out ofl contact with the air. All of this is accomplished without disturbing the furnace linings.

In the somewhat modified form of invention illustrated in Figure 5, the heating ele- Y ,ments are substantial y the same as in Figure 4, except a conductingl mass 35 of copper matte, iron' oxide, or ighly conductive chromite ore is provided, which joins the carbonaceous masses 30 and a by pass conducting member 36 having a coil 37 of a small number of turns. Said member 36 joins the elements 18 and 20 as shown, and

is in inductive relation with the coil 38 havin a relatively large number of turns of'whlch is fed from the source of current 39. An electrode 40 'is placed in contact with'the mass 35,.,

In this particular form of heating element, the current from the source 39 passingY through the coil 38 will be converted from a high voltage into a low voltage of great quantity and such converted current will readily heat up the carbonelement 19, the carbonaceous masses 30 and ore mass 35, and the electrode 40 passing down through the ore to be melted will be withdrawn from said mass'35 as fast as the ore heats up, so that the entire'charge will be melted in a very short space of time.

In the still further modified form of heating elements shown in Figure', the conducting members 18 have led across their top surfaces the heating element 19 which is reduced in cro section as at 42, so that it heats more readily than would be the case it were of a uniform section.

git

Leashes It will now be seen that in all the forms of the invention the furnace may be simply and quickly constructed of ordinary brick-work, the heating elements are readily brought to a high temperature, and impart a high degree of heat to a portion of the charge, thus rendering that portion conductive, so that additional current may pass there through from primary or secondary electrodes.

It will further be noticed that/either a single or multiple phase current may be employed, and that the electrodes proper may be used as arc electrodes or they may be immersed inthe charge and used as resistors according to .the nature of the material to be treated.

It will further be observed that in the form shown in lligure l, the chute 2l and opening 22 into the space 29 are so located that the material is delivered to the hearth in such a Way that it cannot injure the electrodes in itsfall, and that a large, open, un-

obstructed hearth is provided. It will still further be observed that owing to the above mentioned features one is enabled to make a furnace of unusual strength with aminimum of materials and in a minimum of time.

It is obvious that `those skilled in the art may vary the details of construction as well as the arrangement of parts Without departing from the spirit of the invention, and therefore I do not wish to be limited to the above disclosure except as may be required by the claims.

What I claim is:

1. An electric furnace provided with a primary circuit including an arc electrode; a secondary circuit in inductive relation to said primary circuit and including a resistor; comprising a pair of metal conductors with a superposed carbon conductor;

means for preventing the charge material from contacting with said conductors; and means for connecting electrically a charge of ore in the furnace in multiple with said resistor.

2. An electric furnace provided with. a manhole top through which a primary electrode passes; a chute to one side of the chamber with an archway between; means for the gases to escape and for the ore to enter through said chute in combination with a secondary conductor below the hearth comprising a pair of metal conductors surmounted by a carbon conductor and masses of semi-conducting material, the whole constituting a heating element with a parallel circuit through the ore.

3. in electric furnace provided with a charge of material therein; -means to supply heat to the top of the charge from one circuit; means comprising a pair of metallic -bars surmounted by a carbon rool and masses of semi-conducting material separated by insulating material to supply heat from below the charge by another circuit; and additional means for passing all of said circlliits through the charge at different anes. g 4. An electric furnace provided with a charge of material; means of passing the primary circuit through said material vertically; means comprising a pair of metallic bars surmounted by a carbon rod and masses of semi-conducting material separated by'insulating material for passing the secondary circuit through said charge horizontally; and additional means for supplying heat from below the hearth by heating the bottom of the furnace, all from the same energizing circuit.

In testimony whereof I aiiiX my signature.

PARVIN WRIGHT. 

